| 摘要 |
PROBLEM TO BE SOLVED: To provide a conversion device of a speech code string, capable of converting a code string by a small arithmetic amount. SOLUTION: In addition to a circuit for combining a decoding signal from the code string of a Code-Excited Linear Prediction (CELP) system at an input side, a circuit in which an LP coefficient and a pitch period respectively decoded by an LP coefficient decoding circuit 12 and a pitch component decoding circuit 13 are directly forwarded to each of the LP coefficient coding circuit 31 and a pitch component calculation circuit 40 at an output side, and supplied for code string conversion at the output side, is added. Thereby, LP analysis and selection of a pitch period candidate, which are conventionally performed for the decoding signal at the output side become unnecessary. When a band expansion processing is necessary at each of input and output sides, a circuit of band expansion conversion and pitch period candidate generation is added, and a coding circuit is provided instead of pitch component calculation. When a frame length of the input side is longer than that of the output side in the LP coefficient and the pitch period, interpolation is performed, and when it is shorter, average processing is performed. COPYRIGHT: (C)2009,JPO&INPIT
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